1. Field of the Invention
The present invention relates to infrared radiation detection, and, more particularly, to a process for fabricating a front surface resonant mesh array detector.
2. Description of Related Art
A front surface resonant mesh array detector employs an array of photodetector elements formed of an intrinsic photoconductive material, such as HgCdTe, to sense infrared radiation. The photodetector elements are positioned at a front surface of the detector so that they are directly exposed to incoming infrared radiation. In operation, the dc impedance of the photodetector elements varies in response to the level of infrared radiation received at the front surface of the detector. Thus, the dc impedance of the detector is monitored to sense the level of incoming radiation. A resonant cavity can be formed behind the photodetector elements to improve the responsivity of the detector to infrared radiation. The responsivity of the detector could be further enhanced by reducing the size of the photodetector elements. However, existing processes for fabricating a front surface resonant mesh array detector produce a relatively large detector.
In addition, it is difficult to construct area arrays or time delay and integration (TDI) arrays with detectors fabricated from the existing processes, due to the thermal mismatch between the large detector and the substrates used to fabricate such arrays. Thermal mismatch causes structural stress that increases as a function of the size of the detector relative to the substrate. Thus, the relatively large size of the detector fabricated by existing processes results in a significant level of thermal stress that inhibits the fabrication of area or TDI arrays using such detectors.
In light of the foregoing, a process for fabricating a front surface resonant mesh array detector of reduced size is desirable to minimize thermal stress problems that presently prevent the fabrication of area or TDI detector arrays. Moreover, a process for fabricating a front surface resonant mesh array detector of reduced size, while maintaining good quantum efficiency, is desirable to increase the responsivity of the detector.